如何在活动之间传递drawable [英] How to pass drawable between activities

问题描述

如何在活动之间传递图像、可绘制类型?

How can I pass an image, drawable type between activities?

我试试这个:

private Drawable imagen;

Bundle bundle = new Bundle();
bundle.putSerializable("imagen", (Serializable) unaReceta.getImagen());
Intent myIntent = new Intent(v.getContext(), Receta.class);
myIntent.putExtras(bundle);
startActivityForResult(myIntent, 0);

但它向我报告了一个 execption:

But it reports me an execption:

java.lang.ClassCastException: android.graphics.drawable.BitmapDrawable

推荐答案

1) 将 Intent 作为 extras

1) Passing in intent as extras

在 Activity A 中，您解码图像并通过意图发送:

In the Activity A you decode your image and send it via intent:

• 使用此方法(额外)图像以 162 毫秒的时间间隔传递

• Using this method (extras) image is passed in 162 milliseconds time interval

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);     
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos); 
byte[] b = baos.toByteArray();

Intent intent = new Intent(this, ActivityB.class);
intent.putExtra("picture", b);
startActivity(intent);

在 Activity B 中，您接收带有字节数组(解码图片)的 Intent 并将其作为源应用到 ImageView:

In Activity B you receive intent with byte array (decoded picture) and apply it as source to ImageView:

Bundle extras = getIntent().getExtras();
byte[] b = extras.getByteArray("picture");

Bitmap bmp = BitmapFactory.decodeByteArray(b, 0, b.length);
ImageView image = (ImageView) findViewById(R.id.imageView1);

image.setImageBitmap(bmp);

2) 保存图像文件并将其引用传递给另一个活动

2) Saving image file and passing its reference to another activity

• 为什么要这样做? - 取自 http://groups.google.com/group/android-developers/browse_frm/thread/9309931b3f060284#

• WHY to do so? - taken from http://groups.google.com/group/android-developers/browse_frm/thread/9309931b3f060284#

"大小限制是:尽量小.绝对不要放除非它不大于图标(32x32 或随便).

"The size limit is: keep it as small as possible. Definitely don't put a bitmap in there unless it is no larger than an icon (32x32 or whatever).

• 在 *Activity A* 中保存文件(内部存储)
  • In *Activity A* save the file (Internal Storage)

    String fileName = "SomeName.png";
    try {
        FileOutputStream fileOutStream = openFileOutput(fileName, MODE_PRIVATE);
        fileOutStream.write(b);  //b is byte array 
                                 //(used if you have your picture downloaded
                                 // from the *Web* or got it from the *devices camera*)
                                 //otherwise this technique is useless
        fileOutStream.close();
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
    

    • 将位置作为字符串传递给活动 B
      • Pass location as String to Activity B

        Intent intent = new Intent(this, ActivityB.class);
        intent.putExtra("picname", fileName);
        

        • 在*Activity B*中检索文件
          • In *Activity B* retrieve the file

            Bundle extras = getIntent().getExtras();
            String fileName = extras.getString("picname");
            

            • 从图片中制作*drawable*
              • Make *drawable* out of the picture

                File filePath = getFileStreamPath(fileName);
                Drawable d = Drawable.createFromPath(filePath.toString());
                

                • 将其应用于 ImageView 资源
                  • Apply it to the ImageView resource

                    someImageView.setBackgroundDrawable(d);
                    

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